As a large-scale projection display system, a multi-projection display system is known that projects images onto a screen from a plurality of projector units and that joins each of the projected images together to display them as a single image.
In this type of multi-projection display, variation in the brightness on the screen of each of the images projected from the plurality of projector units greatly influences the quality of the overall projected image.
For example, when the brightness of the projected images differs for each projector unit, the seams between each of the images that are projected on the screen become apparent, greatly detracting from the display quality. Accordingly, the brightness of the projected images for each of the projector units must be accurately matched.
As an example of a method for dealing with this problem, Patent Document 1 discloses projecting a plurality of test images that are mutually non-interfering and independent onto a screen from each of the projector units, capturing each of the test images that are projected onto the screen by a measurement camera that is positioned in front of the screen and measuring the brightness for each image, and then adjusting the brightness among each of the images based on the measurement results.
However, in the above-described multi-projection display system of the background art, an increase in the number of projector units that accompanies enlargement of the screen size results in increased complexity of the processing of the main control unit that implements unified control of the brightness of the projected images of each of the projector units as well as a massive increase in the amount of processing, which leads to the problem in which it becomes difficult to increase the number of projector units.
In addition, when the screen size of the multi-projection display system increases, the range that is captured by the measurement camera must be expanded and the distance between the screen and the measurement camera must be increased. As a result, slimming the thickness of the multi-projection display becomes problematic.